1. Field of the Invention:
This invention relates to cellular glass coated with an inorganic substance which improves its heat insulating property.
2. Description of the Prior Art:
Lightweight cellular glass is obtained by adding a foaming agent, such as calcium carbonate or carbon powder, to glass powder consisting mainly of silicon oxide, and heating the mixture. This cellular glass has many independent air cells, and is, therefore, low in bulk density and thermal conductivity. It is also impervious to moisture and water. Therefore, it is widely used in sheet form as a heat-insulating material for buildings, storage tanks for liquefied natural gas, or the like.
When this cellular glass is used as a building material or an inner wall facing for a chimney or the like, however, its surface is subject to damage upon exposure to flame. This and other problems impose a serious limitation on the scope of applications for which the conventional cellular glass can be effectively employed.